Visual Basic.NET - Como manipular txtbox creado con codigo

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        For m As Integer = 0 To 599

            Dim B As New TextBox

            Me.Controls.Add(B)

            B.Height = 30

            B.Width = 25

            B.Left = B.Width * (m Mod 30)

            B.Top = B.Height * (m \ 30)

            B.Text = m

            B.Tag = m

            B.Name = i

        Next

    End Sub

Dim Ctl As Control

        For Each Ctl In Me.Controls

            If TypeOf Ctl Is TextBox Then

                If Ctl.Name = "TextBox1" Then

                End If

            End If

        Next